Analysis of Piezocone Penetration under Different Drainage Conditions with the Two-Phase Material Point Method

Abstract

The piezocone penetration test (CPTU) is commonly used to identify a soil’s profile and estimate its material properties. Depending on the soil type, ranging from clay to sand, undrained, partially drained, or drained conditions may occur during cone penetration. In silt and sand–clay mixtures, the CPTU penetration is characterized by partially drained conditions, which are often neglected in data interpretation. The effect of drainage on CPTU measurements has been mainly studied experimentally. Numerical analyses are rare because taking into account large soil deformations, soil–water and soil–structure interactions, and nonlinear soil behavior is still a challenging task. This paper presents and discusses numerical simulations of CPTU in saturated soils with the two-phase material point method. Soil behavior is described with the modified cam clay model. This study investigates the effects of pore pressure dissipation during penetration, cone roughness, and horizontal stress state, comparing the results with experimental data. The paper discusses the effect of neglecting partial drainage in deriving the shear strength parameters for silty soils and suggests a procedure to estimate the consolidation coefficient for performing CPTU at different penetration rates.